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When using not in, not like, <>, not between in sql, you should pay attention, if the field is permit to null, the null value record can not be selected, you should add not null to let the null record shown. But the not exists is the except, it can select the null record, because the sql is always not exists(select field1 from table1 where table1.field1=table2.field1), if it table2's field1 is null, of course the equation is not true.[@more@]

The recyclebin is just a virtual storage area, a data dictionary. When drop table, the real space on the tablespace this table take up would not deleted in deed. But if the space is not enough, Oracle will delete the space auto.[@more@]

truncate 能释放表空间以及索引空间，但是前一次扩展的索引空间并不一定能记录到数据字典中， 故最好rebuild index.[@more@]

free space 大于db file的大小遇到一个奇怪的问题， db file free space的大小大于file的大小。导致在toad下看到的使用率为负的select sum(bytes) from dba_free_space where file_id=8;result: 35672489984 (这个大小已经达到了数据文件的max)select bytes from dba_data_files where file_id=8;result: 10171187200由于oracle bug 5083393 导致， solution:purge tablespace TS_NAME;exec dbms_space_admin.tablespace_rebuild_bitmaps('TS_NAME');[@more@]

When you use form in html, you can have two value "post" or "get" for method get: With the HTTP "get" method, the form data set is appended to the URI specified by the action attribute (with a question-mark ("?") as separator) and this new URI is sent to the processing agent. post: With the HTTP "post" method, the form data set is included in the body of the form and sent to the processing agent. If use get, your action is "test.html?test=1&

move oracle from '/opt' to '/disk'>shutdowncp all files;update environment.update pfile,change control files, background_dump_dest, core_dump_dest, user_dump_destsqlplus "/as sysdba"> startup mount pfile='new'>alter database rename file 'old' to 'new'>alter database openok[@more@]